From a72b2688bda87a20d029e80eaf8d6686ca95003e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Ekl=C3=B6f?= <daniel@ekloef.se>
Date: Wed, 2 Jun 2021 17:48:57 +0200
Subject: [PATCH] slave/spawn: restore SIGHUP handler after fork(), before
 exec()

Foot installs a SIG_IGN handler for SIGHUP. Ignored signals are
inherited in sub-processes. Thus, we need to restore it to SIG_DFL
before exec:ing.
---
 CHANGELOG.md | 1 +
 slave.c      | 6 ++++--
 spawn.c      | 4 ++++
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7e727ad6..f38db526 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -151,6 +151,7 @@
   in the right-most column.
 * Multi-column characters being cut in half when resizing the
   alternate screen.
+* Restore `SIGHUP` in spawned processes.
 
 
 ### Security
diff --git a/slave.c b/slave.c
index 6a431d02..8e800214 100644
--- a/slave.c
+++ b/slave.c
@@ -274,10 +274,12 @@ slave_spawn(int ptmx, int argc, const char *cwd, char *const *argv,
             _exit(errno_copy);
         }
 
-        /* Restore signal mask */
+        /* Restore signal mask, and SIG_IGN'd signals */
         sigset_t mask;
         sigemptyset(&mask);
-        if (sigprocmask(SIG_SETMASK, &mask, NULL) < 0) {
+        if (sigprocmask(SIG_SETMASK, &mask, NULL) < 0 ||
+            sigaction(SIGHUP, &(struct sigaction){.sa_handler = SIG_DFL}, NULL) < 0)
+        {
             const int errno_copy = errno;
             LOG_ERRNO_P(errno, "failed to restore signals");
             (void)!write(fork_pipe[1], &errno_copy, sizeof(errno_copy));
diff --git a/spawn.c b/spawn.c
index 99f1dc7e..22f0d1ed 100644
--- a/spawn.c
+++ b/spawn.c
@@ -44,6 +44,10 @@ spawn(struct reaper *reaper, const char *cwd, char *const argv[],
         if (sigprocmask(SIG_SETMASK, &mask, NULL) < 0)
             goto child_err;
 
+        /* Restore ignored (SIG_IGN) signals */
+        if (sigaction(SIGHUP, &(struct sigaction){.sa_handler = SIG_DFL}, NULL) < 0)
+            goto child_err;
+
         bool close_stderr = stderr_fd >= 0;
         bool close_stdout = stdout_fd >= 0 && stdout_fd != stderr_fd;
         bool close_stdin = stdin_fd >= 0 && stdin_fd != stdout_fd && stdin_fd != stderr_fd;